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We derive a formula for the Milnor class of scheme-theoretic global complete intersections (with arbitrary singularities) in a smooth variety in terms of the Segre class of its singular scheme. In codimension one the formula recovers a…

Algebraic Geometry · Mathematics 2013-11-19 James Fullwood

We give an elementary proof of the fact that a pure-dimensional closed subvariety of a complex abelian variety has a signed intersection homology Euler characteristic. We also show that such subvarieties which, moreover, are local complete…

Algebraic Topology · Mathematics 2018-04-24 Eva Elduque , Christian Geske , Laurentiu Maxim

This note is mostly an exposition of an unpublished result of Deligne, which introduces an analogue of perverse $t$-structure on the derived category of coherent sheaves on a Noetherian scheme with a dualizing complex. Construction extends…

Algebraic Geometry · Mathematics 2010-06-24 Roman Bezrukavnikov

Torsion sensitive intersection homology was introduced to unify several versions of Poincare duality for stratified spaces into a single theorem. This unified duality theorem holds with ground coefficients in an arbitrary PID and with no…

Geometric Topology · Mathematics 2023-09-27 Greg Friedman

We study intersection theory for differential algebraic varieties. Particularly, we study families of differential hypersurface sections of arbitrary affine differential algebraic varieties over a differential field. We prove the…

Logic · Mathematics 2015-02-25 James Freitag

Given a perversity function in the sense of intersection homology theory, the method of intersection spaces assigns to certain oriented stratified spaces cell complexes whose ordinary reduced homology with real coefficients satisfies…

Algebraic Topology · Mathematics 2019-10-23 Markus Banagl , Eugenie Hunsicker

This paper is the first in a series. The main goal of the series is to present a geometric construction of certain remarkable tensor categories arising from quantum groups coresponding to the value of deformation parameter $q$ equal to a…

High Energy Physics - Theory · Physics 2008-02-03 M. Finkelberg , V. Schechtman

Let $X$ be a real algebraic variety with set of complex points $X_{\mathbb C}$ and set of real points $X_{\mathbb R}$. A complex slice of $X$ is a transverse intersection of $X_{\mathbb R}$ with a complex subvariety $V$ of $X_{\mathbb C}$.…

Algebraic Geometry · Mathematics 2025-11-26 Oleg Viro

In previous works, we studied intersection homotopy groups associated to a Goresky and MacPherson perversity and a filtered space. They are defined as the homotopy groups of simplicial sets introduced by P. Gajer. We particularized to…

Algebraic Topology · Mathematics 2026-05-14 Martintxo Saralegi-Aranguren , Daniel Tanré

Let $M=G/H$ be a Riemannian homogeneous space, where $G$ is a compact Lie group with closed subgroup $H$. Classical intersection theory states that the de Rham cohomology ring of $M$ describes the signed count of intersection points of…

Differential Geometry · Mathematics 2025-02-13 Paul Breiding , Peter Bürgisser , Antonio Lerario , Léo Mathis

Intersection cohomology is a way to enhance classical cohomology, allowing us to use a famous result called Poincar\'e duality on a large class of spaces known as stratified pseudomanifolds. There is a theoretically powerful way to arrive…

Algebraic Topology · Mathematics 2022-12-08 Sebastian Cea

We show that for a complete complex algebraic variety the pure component of homology coincides with the image of intersection homology. Therefore pure homology is topologically invariant. To obtain slightly more general results we introduce…

Algebraic Geometry · Mathematics 2007-05-23 Andrzej Weber

We consider intersecting hypersurfaces in curved spacetime with gravity governed by a class of actions which are topological invariants in lower dimensionality. Along with the Chern-Simons boundary terms there is a sequence of intersection…

High Energy Physics - Theory · Physics 2015-06-26 Elias Gravanis , Steven Willison

We generalize two classical formulas for complete intersection curves by introducing the the complete intersection discrepancy of a curve as a correction term. The first is a well-known multiplicity formula in singularity theory, due to…

Algebraic Geometry · Mathematics 2026-04-07 Andrei Benguş-Lasnier , Antoni Rangachev

In this paper, We develop the stratified de Rham theory on singular spaces using modern tools including derived geometry and stratified structures. This work unifies and extends the de Rham theory, Hodge theory, and deformation theory of…

Algebraic Geometry · Mathematics 2025-08-05 Jiaming Luo , Shirong Li

We prove that a complete intersection of $c$ very general hypersurfaces of degree at least two in $N$-dimensional complex projective space is not ruled (and therefore not rational) provided that the sum of the degrees of the hypersurfaces…

Algebraic Geometry · Mathematics 2019-09-13 Lucas Braune

This paper has two aims. The former is to give an introduction to our earlier work on the Hodge theory of algebraic maps and more generally to some of the main themes of the theory of perverse sheaves and to some of its geometric…

Algebraic Geometry · Mathematics 2007-05-23 Mark Andrea A. de Cataldo , Luca Migliorini

A multisection of a 4-manifold is a decomposition into 1-handlebodies intersecting pairwise along 3-dimensional handlebodies or along a central closed surface; this generalizes the Gay-Kirby trisections. We show how to compute the twisted…

Geometric Topology · Mathematics 2024-02-21 Delphine Moussard , Trenton Schirmer

Let $X \subset \Bbb P^r$ be a smooth algebraic curve in projective space, over an algebraically closed field of characteristic zero. For each $m \in \Bbb N$, the $m$-flexes of $X$ are defined as the points where the osculating hypersurface…

alg-geom · Mathematics 2008-02-03 Fernando Cukierman

We apply methods of derived and non-commutative algebraic geometry to understand intersection theoretic phenomena on arithmetic schemes. Specifically, we categorify Bloch's intersection number (in the formulation provided by Kato--Saito).…

Algebraic Geometry · Mathematics 2024-10-04 Dario Beraldo , Massimo Pippi